Bell hoist system



Dec. 2, 1941. G. Fox

BELL HOIST SYSTEM Filed Dec. 22, 1938 'l JNVENTOR.

Grdon Fox A Troie/ways.

Patented Dec. 2, 1941 BELL HOIST SYSTEM Y Gordon Fox, Chicago, IIL,assignor to Freyn Engi neering Company, Chicago, IIL, a corporation ofMaine Application December 22, 1938, Serial No. 247,257

1,0 Claims- 'I'he present invention relates to ybell hoist systems.

In a blast furnace it isk common practice to provide two charging bellsin series at the top of the blast furnace. One of said bells, which isuppermost, is commonly termed the small bell and the other is commonlytermed the large bell. The material to be charged into the blast furnaceis deposited on the small bell, after which the small bell is opened toallow said material to deposit upon the large bell. After the small bellhas opened a plurality of times to discharge material upon the largebell, `the large bell is opened to discharge this material into theblast furnace. Only one ofthe bells should be open at any one time.

-Various types of means have been provided for operating the large andsmall bells, but due to the size and weight of the parts problems havebeen encountered which have not been entirely solved by means now knownand used.

An object of the present invention is to provide a combined hydraulicand pneumatic operating system which will be positive in operation andwhich will avoid slamming of the parts.

A further object is to provide bell operating means which are simple,which are positive in operation andwhich may be readily controlled.

A further object is to provide a'bell operating system involving areservoir of compressed air whereby even though the primary motivemeans, such for example as electrical supply means, should fail,nevertheless operations may be continued to a material extent.

"A further object isy to provide a bell operating system having theadvantages above referred to which is so safeguarded that in the eventof failure of the primary motive means, cr of the hydraulic or pneumaticmeans, the result will be had that one of the bells will beautomatically moved to closed position.

A further object is to provide an improved bell hoisting system Welladapted to meet the needs of commercial service.

Further objects will appear as the description proceeds.

Referring to the drawing- Figure 1 is a diagrammatic view illustratingone embodiment of the present invention; and

Figure 2 illustrates a detail of construction.

The numeral I0 indicates a blast furnace provided at the top thereofwith the -conical Vportion II adapted to be closed by the large bell I2.

Coaxially disposed with the conical portion I I f is the con-ical.portion I Sadapted to be closed by the small bell I4. The'numeral I 5indicates an enclosure for the top part of the furnace connecting theconicalr portion II with the conical portion I3. Said bells I4 and I2are shown separated in the drawing for purposes of convenientillustration. According to usual practice said bells will be coaxiallydisposed. The large bell I2 is provided with the operating member I6,which, through the 'lever II, is connected to the cable I8. The numeralI 9 indicates an operating cylinder for the large bell, which operatingcylinder is provided with the piston 26 and the piston rod 2 I. Saidcable IS is connected to the upper extremity of the piston rod 2 l. Thespace below the piston 2li is connected to atmosphere. In order toprevent the waste of oil which may seep past the piston 20, the lowerextremity of the cylinder I9 is connected through the pipe 22 to the oilreservoir 23, which is at atmospheric pressure, The upper extremity ofthe cylinder I9 is connected through a series of piping with the oilpressure tank 2a. The piping connecting the upper portion of the la-rgebell cylinder I9 with the oil pressure tank 24 includes the pipe 25, theoperating valve 26, the pipe 2l and the pipe 28. C'onnected in saidApipe 2l is the regulating valve 29, which has the function of regulatingthe speed of the piston 2i) on its down stroke. Connected in parallelacross the regulating valve 29 is the cneckvalve by-pass 35. Connectedto the oil pressure tank 24 through the pipe 28 is the pipe 3l leadingto the oil reservoir 23. Disposed in said pipe 3l is the relief valveSla. Connecting the operating valve 26 with the pipe 3l is the pipe 3Ibprovided with the regulating valve 3 Ic. The large bell I2 is biased toopen even when unloaded. In other words, it is necessary, in order tohold the large bell I2 in closed position, to exert oil pressure uponthe piston 20 in the large bell cylinder I9, so that said piston 2 5 isat or near the bottom of its stroke.

Referring now to the operating means for the small bell ill, said smallbellV has connected thereto the operating member 32, which, through thelever 33, is connected to the cable 34. A

The numeral 35 indicates an operating cylinder for the small bell, whichcylinder is provided with the piston 35 having the piston rod 31. Saidpiston rod 31 is stationary and is provided an axial bore -38 throughwhich oil may be admitted to raise the cylinder 35. The lower side ofthecylinder 35 is connected to the oil reservoir 23 vthrough the `pipe 38a,vwhich may be flexible to permit movement c f cylinder 35. Said cylinder35 is provided with the counterweightsv 39, whereby said cylinder 35will bias the small bell I4 to closed position even when said small bellI4 is loaded with its burden.

The numeral 49 indicates a pipe connected to the bore 38 of the pistonrod 3'I. Said pipe 49 is connected to the operating valve 4I, and thepipe 42 connects the operating valve 4| to the pipe 28 which leads tothe pressure tank 24. Disposed in said pipe 42 is the regulating valve43 for regulating the up-stroke of the cylinder 35. Said operating valve4I is also connected through the pipe 44 to the oil reservoir 23, whichis at atmospheric pressure. Disposed in said pipe 44 is the regulatingvalve 45 for regulating the downstroke of the cylinder 35.

The numerals 46-46 indicate oil pumps for discharging oil from the oilreservoir 23 to the pressure tank 24, check valves 47-41 being providedbetween said pumps 46-46 and said oil pressure tank 24. Said pumps46--46 are operated by the motors 48-48. The numeral 49 indicates an airpump for maintaining a predetermined pressure of air within the oilpressure tank 24, said air pump 49 being connected to said oil pressuretank 24 through the pipe 5U, which pipe U is provided with the checkvalve 5I. A vent valve 52 is provided to prevent the application ofexcess air pressure to the oil pressure tank 24. The numeral 53indicates a pressure gauge for the oil pressure tank 24. The term air asused in this specication is to be construed to include gas and air. Onetype of operating valve which may be used in the practice of the presentinvention is illustrated in Figure 2, wherein the casing 54 provides acylinder for housing the operating rod 55. Said operating rod 55 isprovided with the pair of pistons 56 and 5l. Said pistons 56 and 51 areadapted to control the ports 58 and 59 respectively. The casing 54 isprovided with the port 60 communicating at all times with the spacebetween the pistons 56 and 5l. The operating rod 55 is controlled by thepiston rod 6l, which in turn may be controlled by any preferred means.It will be clear that in the positions of the parts illustrated inFigure 2, communication is had between the ports 58 and 60, whereas theport 59 is closed. With the operating rod 55 in its uppermost positioncommunication will be had between the ports 59 and 60, whereas the port58 will be closed. The operating valve is indicated by the numeral 26.

The mode of operation of the above described embodiment of the presentinvention is substantially as follows: Inasmuch as the large bell I2 isnot counterweighted it must be held closed by oil which lls the chamberof the cylinder I9 above the piston 20. This oil is under high pressure.In order to close the large bell I2, oil is forced from the pressuretank 24 into the upper portion of the large bell cylinder I9. This isdone by movement of the operating valve 26. The speed of the downwardmovement of the piston 20 can be controlled by adjustment of theregulating valve 29. In its movement to close the large bell I2 thepiston 29 travels downwardly in the large bell cylinder I9n until thelarge bell I2 seats and until tension in the bell cable places a sealingpressure lon the large bell. 'I'he cable pull is determined by the oilpressure. In the event of an explosion between the bells, the pull uponthe cable I8 is restricted pneumatically, because the air in thepressure tank can be practicallyinstantaneously compressed to a degreesufficient to permit enough movement of the large bell I2 to relieve thepressure on the bell. A substantial movement of the bell will not causea great increase in pressure in the pressure tank 24 because of thecompressibility of the air therein. The relief valve 3| a provides forfurther relief through flow of oil from the pressure tank 24 throughsaid relief valve 3la to the oil reservoir in the event that thepressure in the pressure tank rises sufficiently.

In the event of an explosion between the large bell I2 and the smallbell I4 there will be a tendency for the large bell cable I8 to pullupward on the piston 29 in the large bell cylinder I9, therebyincreasing the oil pressure in said cylinder I9. This oil pressure istransmitted directly back through the operating valve 26 and through theregulating valve 29 to the pressure tank 24. Because the regulatingvalve 29 serves as a restriction, the check valve by-pass 30 operates toby-pass said regulating valve 29. This permits the ready flow of oil ina direction from the large bell cylinder I9 toward the pressure tank 24.The pressure tank 24 is partly iilled with oil but has a compressed airspace above the oil. The compressed air space acts as a cushion whichprevents any sudden impact stresses such as would otherwise becharacteristic of a hydraulic system. The compressed air gives to theentire system certain desirable characteristics of a pneumatic system,particularly with reference to limiting the cable pulls and possiblestresses.

In the event that an explosion between the large bell I2 and the smallbell I4 is sufficient to substantially raise the pressure of the oil inthe pressure tank 24 by compressing the air therein, the pressure willbe limited by operation of the relief valve Sla, which discharges oil tothe reservoir 23. In the event that an explosion causes upward movementof the piston 20 in the large bell cylinder I9, said piston will againmove downwardly to close the large bell as soon as the pressure in thehopper between the bells is relieved.

It should be noted that no limit switches are required and that thelarge bell seats in a cushioned manner due to the air in the pressuretank.

To open the large bell I2', the operating valve 26 is operated toprovide communication between the cylinder I 9 and the pipe 3Ib topermit discharge of oil from Y the large bell cylinder I9 through theregulating valve 3Ic to the oil reservoir 23, which is at atmosphericpressure. Said regulating valve 3Ic can be adjusted to control the rateof movement of the large bell. The bell cylinder I9 in conjunction withthe valve 3Ic acts as an oil dashpot to restrict the opening speed ofthe large bell. According to the present invention the weight of thepiston 20 is negligible in comparison to the parts with which it isconnected plus the burden on the large bell, and gravity is dependedupon as the sole motive means for opening the large bell. Thisconstruction is to be distinguishedyfrom the construction of pneumatichoists in which pressure is applied below the piston to lift the weightof the operating parts, plus any counterweights which may be connectedthereto. The construction according to the present invention tends tostart to open more quickly than a pneumatic hoist because nocounterweig-hts are used in connection with the cylinder I9 or itspiston 2l).

The small bell I4 is operated through the cylinder 35. It is preferredto'counterweight the small bell i I4 suliiciently to hold it closedagainst maximum burden which may .be imposed thereon Thus the `smallbell Mwill be opened only when and if oil is introduced under pressureabove the piston 35 vto .lift the cylinder ,35? thereby permit.- tingthe small bell I4 to open by gravity.

Oil :for operation of the small bell I4 is introduced tc the srnallbellcyllnder v35 through the operating valve 4l adjacent to the basethereof. 'lhe speed ofopening of the small bell can be controlled bymeans of the regulating valve 4.3.. '.lhelower side or the small. bellcylinder 35 is connected to the oil reservoir 23 through the pipe 35o,being thereby subjected to atmospheric pressure. l l When the small bellI4 is to be closed, the operating valve 4I is moved to connect the pipe4I)` with the pipe 44. The space above the piston 3b is therebyconnected rto the oil reservoir 23 through the regulating valve 45, andoil is permit-ted to pass out of. the upper portion of the srnall .bellcylinder 35 to the oil reservoir The speed' of opening of this bell canbe controlled by adjusting the Vregulating valve .45V l the operationlof the two bells oil is taken from the oil pressure tank 274 landdelivered to the oil reservoir 23. I n turn oil is removed from thereservoir 2'3 by rneans of the ptunps 45-46 which deliver oil back tothe pressure tank Z4. By .delivering oil to the pressure tank 24 thesepumps tend to compress the air in said tank 24 to raise the pressuretherein. Incidentally the air pump all may be used, if necessary. tointrodue air into the pressure tank 244 the event that there is agradual loss of air therein due to diffusion in the o il leaving saidpressure tank 24. In further explaining the functions of the air pump49, let it be assumed that the tank 24 is empty and that the airthereinis at atmospheric pressure. If oil be now delivered to this tank, theexits therefrom being closed,V the air pressure within the .tankv Willapproximate twice atmospheric pressure when theltank is half full ofoil. It will be evident that in order to secure a high pressure in thistank while still retaining a substantial volume of air for cushioningpurposes, it is not feasible to start With atmospheric presure in thetank...l Y

, If the above operation be repeated with a-ir at 1Q() pounds pressureinthe empty tank, the pressure would be approximately D pounds persquare, inch when the tank is half full of oil. Similarly, if.compressor 49 is of the type which can deliver air at 200 pounds persquare inch pressure, it will be possible to introduce air at suchpressure into the empty tank and then by pumping oil therein to increasethe pressure to about 40.0 pounds per square inch vwith the tank halffull of Oil.-

AIn practice it will be preferred to use high oil pressures-and it isalso desirable that the volume of the compressed air, suitable forcushioning purposes vin tank 2'4, be substantial. In order to accomplishthese relations the compressor 49 is provided, which functions todeliver air at an initial increased pressure to theempty tank, usingpumps 4S as booster pumps to further increase the air pressure of theair cushion in reservoir 24. It will be observed that inthe operation ofthe bells there is a tendency to reduce the pressure within the pressuretank 24. Continued operation would eventually drop` the pressure in thepressure tank below operative adequacy. lrlovv-` ever, by suitablypl'oportioning the pressure tank with reference to the 4-vcuurne of thebell cylinders t9 and .35, the. air compressed in the pressure tankserves as a yreserve motive means whereby the system can .be operativeto a limited extent with out reference to the pump, This is an importantfeature as it gives a degree of reliability in that operation of thebells is not dependent upon electric power orY any external sourceofpower, so long as adequate pressure remains within the tank 24, Duringthe time that the large bell I2 is being closed, oil ilows from thepressure tank g4 to thelarge bell cylinder I9 at a high rate. Thisaction occurs only for a short period, such as in theneighborhocd of tenor twenty seconds.. This period is. normally followed by a rnuch longerperiod. during which material is being deposited upon the large bell.The rate' of delivery of oil from the pumps t.lt--Jili to the pressuretank 24 ismuch less than the rate of flow from the pressure tank .24 tothe large bell cylinder IS. `Such a relation is possible because of thefact thatthe large bellcylinder Lis in movement only a small fraction ofthe total time. Because of the relationship just'rnentoned, a smallmotor and 4a pump equipment, operating not necessarily contlnuously butoperating a large portion of the time, serves to supply the motive powerfor. the entire system- 'lhe peak demands, .caused by movement of thelarge bell, are not transmitted directly back to the electrical system,nor is it necessary to. supply a large motor and a heavy mechanismcapable et handling such a short time peak load. A motor equipment isperhaps onefifth the size of the motor that would be required to handlethe load directly without the introduction of the compressed air featurewhich serves @S a DOWGI Storage means- As previously stated, the largebell I2 is biased to open and is kept closed only by the oilpressurewithin the large bell cylinder I9. If the oil pressure should,fail, the large bell would open, The small bell is biased to closedposition even when burdened, and is caused to open byreason ofapplication of oil pressure. Therefore, inthe event of failure of theoil pressure the small bell Will close and will remain closed. Thereforethe advantage had that in the event .of a failure of oil pressure one 0fthe two bells will be closed.

The hydro-pneumatic hoist system hereinabove described requiresrelatively small cylinders and is adapted to have a ycompactarrangement. No large counterweight is required for the large bell, andfor at least a short period of time the system may be independent of theelectric supply or other outside power supply. It involves the use of nolimit switches and permits cushioned seating of the bells and limitedcable pulls.

Though a preferred embodiment of the present invention has beendescribed in detail, many modifications will occur to those skilled theart, Itis intended to cover all such modications that fall within thescope of the appended claims,

What is claimed is- 1. In a bell hoist system, in combination, a pair ofbells in series with each other, each of which moves upwardly to closeand downwardly to open,- a bell cylinder for operating one of saidbells, a bell cylinder for operating the other of said bells, said onebell requiring a certain amount .of pressure in its corresponding`cylinder to maintain same closed even when unloaded, said other bellbeing biased to closed position even when loaded,v a pressure tankadapted to contain liquid and compressed air, a reservoir for liquid,means for seleotably directing liquid from said pressure tank to saidcylinder 4for said one bell or for directing liouid from .said.first-mentioned .cylinderto said;

reservoir, means for selectably directing liquid from said pressure tankto said cylinder for said other bell or from said last mentionedcylinder to said reservoir, and means for returning liquid underpressure from said reservoir to said pressure tank, whereby acirculation of oil is had between said reservoir and said pressure tankby reason of the elevating and lowering of said weighted member. I

2. In a bell hoist system, in combination, a pair of bells in serieswith each other, each of which moves upwardly to close and downwardly toopen, a bell cylinder for operating one of said bells, a bell cylinderfor operating the other of said bells, said one bell requiring a certainamount of pressure in its corresponding cylinder to maintain same closedeven when unloaded, said other bell being biased to closed position evenwhen loaded, a pressure tank adapted to contain liquid and compressedair, a reservoir for liquid, means for selectably directing liquid fromsaid pressure tank to said cylinder for said one bell or for directingliquid from said first-mentioned cylinder to said reservoir, means forselectably directing liquid from said pressure tank to said cylinder forsaid other bell or from said last-mentioned cylinder to said reservoir,means for returning liquid under pressure from said reservoir to saidpressure tank, whereby a circulation of oil is had between saidreservoir and said pressure tank by reason of the elevating and loweringof said weighted member, and regulating valves for controlling the iloWof liquid from said cylinders to said reservoir.

3. In a bell hoist system, in combination, a pair of bells in serieswith each other, each of which moves upwardly to close and downwardly toopen, a bell cylinder for operating one of said bells, a bell cylinderfor operating the other of said bells, said one bell requiring a certainamount of pressure in its corresponding cylinder to maintain same closedeven when unloaded, saidother bell being biased to closed position evenwhen loaded, a pressure tank adapted to contain liquid and compressedair, a reservoir for liquid, means for selectably directing liquid fromsaid pressure tank to said cylinder for said one bell or for directingliquid from said first-mentioned cylinder to said reservoir, means forselectably directing liquid from said pressure tank to said cylinder forsaid other bell or from said last-mentioned cylinder to said reservoir,means for returning liquid under pressure from said reservoir to saidpressure tank whereby a circulation of oil is had between said reservoirand said pressure tank by reason of the elevating and lowering of saidweighted member, and regulating valves for controlling the ow of liquidfrom said pressure tank to said cylinders.

4. In a bell hoist system, in combination, a pair of bells in serieswith each other, a bell cylinder for operating one of said bells, a bellcylinder for operating the other of said bells, a pressure tank adaptedto contain liquid and compressed air, a reservoir for liquid, means forselectably directing liquid from said pressure tank to said cylinder forsaid one bell or for directing liquid from said rst-mentioned cylinderto said reservoir, means for selectably directing liquid from saidpressure tank to said cylinder for said other bell or from saidlast-mentioned cylinder to said reservoir, and relief means fordirecting liquid from said pressure tank to said reservoir in the eventof an explosion between said bells.

5. In a bell hoist, in combination, a bell upon which material isdeposited progressively over a period of time to build up a load, meansfor controlling the elevation of said bell comprising an operatingcylinder and a pressure tank, said pressure tank being adapted to bepartly filled with liquid and partly iilled with compressed air, acertain amount of pressure being necessary in said cylinder to maintainsaid bell closed even when said bell is unloaded, a reservoir forliquid, means for selectably directing liquid from said pressure tank tosaid cylinder or directing liquid from said cylinder to said reservoir,and means for increasing the pressure within said pressure tank at arate suicient to hold said bell in closed position in spite of increaseof the weight of said bell and the material deposited thereon, saidpressure increasing means including pumping means for delivering liquidfrom said reservoir to said pressure tank.

6. In a bell hoist system, in combination, a pair of bells in serieswith each other, an operating cylinder for one of said bells, a secondoperating cylinder for the other of said bells, said one bell requiringa certain amount of pressure in its corresponding cylinder to maintainsaid one bell closed even when unloaded, said other bell with itscorresponding cylinder being provided with counterweights to hold saidother bell in' closed position even when loaded, and common pressuremeans for introducing iluid selectably into said cylinders forcontrolling the elevation of said cylinders and consequently thepositions of said bells.

7. In a bell hoist, in combination, a bell upon which material isdeposited progressively over a period of time to build up a load, meansfor controlling the elevation of said bell comprising an operatingcylinder and a pressure tank, said pressure tank being adapted to bepartly filled with liquid and partly filled with compressed air, acertain amount of pressure being necessary in said cylinder to maintainsaid bell closed even when said bell is unloaded, a reservoir forliquid, means for selectably directing liquid from said pressure tank tosaid cylinder or directing liquid from said cylinder to said reservoir,and means for increasing the pressure within said pressure tank at arate suilcient to hold said bell in closed position in spite of increaseof the weight of said bell and the material deposited thereon, saidpressure increasing means including pumping means for delivering liquidfrom said reservoir to said pressure tank, the volumetric capacity ofsaid pressure tank being such that sufficient liquid may be deliveredtherefrom to said cylinder to close said bell Without aid from anyextraneous source of power.

8. In a bell hoist, in combination, a bell upon which material isdischarged progressively to build up a load, an operating cylinder forsaid bell, a certain amount of pressure being required in said cylinderto hold said bell closed even when said bell is unloaded, a pressuretank adapted to be partly filled with liquid and partly lled withcompressed air, and means for introducing iluid into said cylinder fromsaid tank whereby an initial relatively low pressure is applied to closesaid bell and the pressure is increased to retain the bell in closedposition while material is being loaded upon said bell.

9. In a bell hoist system, in combination, a pair of bells in serieswith each other, an operating cylinder for one of said bells, a secondoperating cylinder for the other of said bells, a certain amount ofpressure being required in said rst mentioned cylinder to maintain saidone bell closed, the other of said bells being biased to closedposition, a pressure tank adapted to contain liquid and compressed air,a reservoir for liquid, means for selectably directing liquid from saidtank to said one cylinder or from said one cylinder to said reservoir,means for selectably directing liquid from said tank to said secondvcylinder or from said second cylinder to said reservoir, and means forreturning liquid under pressure from said reservoir to said pressuretank whereby a circulation of oil is had between said 10 reservoir andsaid pressure tank by reason of the elevating and lowering of saidbells.

